The distribution of content often relies upon a content distribution network (CDN) where content is cached closer to the client such that the load demands are off-loaded from an Origin Server. In practice, a content provider or content aggregator will typically refer to a designated CDN that is authorized to distribute the content. From a practical perspective, the designated CDN can only reach a footprint of coverage where it has deployed cache-nodes.
The industry has leveraged global CDN's to distribute content across the Internet; however, these designated CDN's are rarely allowed to insert cache-nodes inside a network provider's infrastructure. In fact, many of the larger network providers are building their own CDN infrastructure in order to control content distribution within its own routed domain. The network provider CDN will either need to serve as a designated CDN from the content provider (clients referred to the CDN explicitly) or serve as a delegate CDN to an upstream designated CDN.